Steam generator



Jan. 16, 1934. K. BAUMANN 1944059 STEAM GENERATOR 4 Filed Aug. 7. 1950 5 Sheets-Sheet 1 Hal.

INVENTOR Karl Baumann,

` w M/M -fAmronuBY `Jam. 16, 1934. K. BAUMANN 1944059 STEAM GENERATOR Filed Aug. 7. 1980 5 sheets-sheet 2 INVENTOR Kar 1 B aumann ATTORNE! K. BAUMANN STEAM GENERATOR Jan. 16, 1934.

Filed Aug. 7, 1930 5 Sheets-Sheet 3 INVENTOR Karl Baummn,

Jan. 16, 1934. K. BAUMANN 1,944,059

STEAM GENERATOR Filed Aug. '7. 1930 5 Sheets-Sheet 5 INVENTOR I Karl Baumann,

BY w

' w dv9770'/ ATTORNEY Patented Jan. 16, 1934 rrss 'TENT OFFICE Application August 7,

1930, Serial No. 473,695,

and in Great Britain August 21, 1929 s olaims.

The invention relates to steam generating systems in which combined direct and indirect methods of generating steam are utilized.

In addition to the usual constructional parts,

the steam generator forming the subject of this invention consists of a number of externally heated water tubes which discharge into one or more boiler drums of the usual type, a number of externally heated superheater elements and one or more heating elements, the latter being arranged in one or more separate evaporators. Alternatively they may be arranged both in the boiler drum or drums and the evaporators.

The direct steam generation is efected in the usual way, either by radiation or convection of heat to the water tubes, or by a combination of both these forms of heat transmission. The directly heated water tubes are preferably arranged around the combustion Chamber in any of the 20 Well known manners. For the purpose of indirect generation, the saturated steam produced in the generator is superheated in two or more stages, between which stages the superheated steam is utilized to generate further steam in one or more evaporators.

The superheated .steam is not mixed with the water to be evaporated in the evaporators. As the fiow of steam through the superheater elements and the heating elements involves a drop in pressure between the saturated steam space or spaces and the generator outlet or outlets, the steam in the heating elements is at a lower pressure than the boiling water on the outside and cannot therefore be cocled to its saturation temperature. This reduces the possibility of scale formation inside the steam tubes.

The steam connections to the first superheater stage may be taken either from the boiler drum or drums or from the evaporator or evaporators or from any suitable point or points in the steam pipes which interconnect the evaporators and drums.

As all the drums and the evaporators are interconnected on the steam side, all the saturated steam produced in the generator is mixed together before entering the first superheater stage. It is then led alternately through the succession of superheater elements and heating elements.

The steam is superheated to the required temperature in a final stage before leaving the generator.

The evaporator drums are provided with surface-heat interchangers, in the form of nests of -tubes disposed therein. instead of providing separate evaporator drums for each nest of evaporator tubes which the steam traverses between consecutive stages of superheating, several nests of evaporator tubes may be contained in a common evaporator drum or casing, or they may be arranged Within the boiler drum itself.

As stated above, the combustion chamber may be of any suitable design and it may be divided from the superheater Chamber by a row or rows of water tubes between which the furnace gases must pass before coming into contact with the superheater tubes.

After passing through the superheater chamber the gases may be further cooled in an economizer and/or air heater in the usual manner. l

The proposed new design of steam generator lends itself to maintaining a constant temperature of the steam leaving the system. This can be done in a variety of ways, for example by varying the water level in the evaporators, or by-passing superheated steam past the evaporator coils. The water level in the evaporators may be Varied inrdifferent ways, for instance by controlling the feed water supply tc the evaporators where a separate feed water supply is provided or in the case where the evaporator drum is connected to the boiler drum on the water side through balance pipes by throttling the steam evaporated in '"ie evaporator or in the boiler drum. The control valves may be operated manually orV by meansl of a Variation in temperature of the steam leaving the system.

The invention is illustrated by way of example by Figs. 1 and 2, which show diagrammatically two preferred arrangements of steam flow in the generator, and Figs. 3,V 4 and 5 which illustrate some of the proposed constructional forms of the generator. For convenience the tubes of the superheater elements and the heating elements vof the evaporators are shown only in single lines, as also are the tubes of the economizers where shown.

Referring to the arrangement shown in Fig. 1, steam is generated in the externally heated water tubes 1 which may be arranged'- and interconnected in any` suitable way, and is discharged into the steam and water drum 2. The saturated steam from drum 2 is led to a junction 3 and thence together with steam from evaporators 4, 5 and 6, through a superheater element 'l where it lis superheated to the required temperature, and is then led through a heating element 8 arranged in the evaporator 4. The steam is cooled in this element thereby evaporating further steam in the evaporator, and is then led through the second superheater element 9, and then in a similar 'indirect generation of steam takes place.

manner through the alternate heating elements 10 and 12 and superheater elements 11 and 13. From the final superheater element 13 the steam is led to a prime mover 14 or other steam Consuming apparatus. The superheater elements 7, 9, 11 and 13 may be arranged either in counter ow to the direction of the furnace gas flow, or they may be arranged in parallel flow, or in counter flow and parallel flow combined, or in any other suitable manner. The steam indirectly generated in the evaporators 4, 5 and 6 is led to the junction 3, Where it mixes with the steam from the drum 2.

in the arrangement shown in Fig. 2 the steam flow is generally similar to Fig. 1 but the heating elements 8, 10 and 12 are all arranged in one evaporator 4.

In the arrangement shown diagrammatically in cross section in Fig. 3, 1 is a combustion chamber suitable for burning liquid, solid, pulverulent or gaseous fuel. The walls ofA the Combustion Chamber' are lined with water tubes 2, 2a etc. which discharge into a steam and water drum 3 and serve for the direct generation of steam. The tubes may be plain or of the fin type, or if desired they may be protected in the known manner from direct exposure to the furnace flame by a covering of refractory or other material.

The water tubes 5, 6, 24 which form the continuation of the water tubes 2 lining the rear of the furnace are formed as shown in the drawings and are provided with fins or Covered with blocks of refractory or other material in their parts 5 and 24 in such a way as to form bafiles, the bafile 5 serving as the bottom of the superheater Chamber 4, and protecting the superheater elements 7 and 8 which are disposed in the Chainber 4 from direct exposure to the furnace fiame. The baflie 24 forms the top of the combustion Chamber and protects the drum 3 from exposure to the heat of the furnace.

The Vertical portion 6 of the tubes lining the upper portion of the combustion Chamber are left bare of fins or other coverings and are staggered alternately to present a larger area for the passage of the flue gases from the Combustion Chamber 1.

27 is an evaporator of the Vertical type wherein The steam space from the evaporator 27 is connected to the drum 3 by means of one or several pipes 10 provided with a throttle valve 32. The total steam generated in the drum 3 and the evaporator 27 passes through the pipe 12 to a superheater element 8 which is disposed at the rear end of the combustion Chamber 4. The steam fiows through this superheater in a Countercurrent direction to the fiow of the flue gases and passes out through the pipe 13. The superheated steam is then desuperheated by passing through tubes 28 in the water space of the evaporator 27 and passes by Vway of the pipe 15 to the final superheater element 7 through which it fiows in the same gen- `eral direction as the flow of the flue gases in the generator by the pipe 16 in a suitable condition for use in the steam utilizing apparatus.

The water space of the evaporator 27 is connected to the water space of the drum 3 by the pipe 35. The heating elements in the evaporator Vconsist of hairpin type tubes 23, both ends of which are expanded into a tube plate 31. The space below the tube plate is divided into two portions, the part 29 serving as the inlet Chamber for the steam flowing through the pipe 13 from the first superheater element 8, and part 30 serving as the outlet Chamber for the steam after it has given up some of its heat while fiowing through the tubes 28 thus evaporating additional steam in the evaporator 27.

The water level in the evaporator 27 can be controlled by manual or automatic means such as for instance by throttling the evaporator steam by means of the valve 32 which may be operated by hand or automatically. The amount of heat given up by the steam ilowing through the hairpin tubes 28 will depend upon the position of the water level in the evaporator 27, and varying this water level gives an effective means of controlling the nal temperature of the steam leaving the steam generator.

The final steam temperature at the generator outlet can also be Controlled by arranging a bypass pipe 33 with a valve 34 between the pipe 13, which conveys the steam to the inlet Chamber 29 of the evaporator 27 and the pipe 15 which leads the steam away from the outlet Chamber 30 of the evaporator 27. The Valve 34 can be hand or automatically Controlled and the quantity of superheated steam by-passing the heating element 28 of the evaporator 27 can thus be regulated. It will be seen that the final steam temperature at the Outlet of the generator will depend upon the amount of heating steam by-passed from the heating element 28.

The combustion products after leaving the superheater chamber 4 pass through an economizer 17 and an airheater 18, which on the drawings is shown to be of the rotating type, and are then conveyed to the chimney. 25 is a forced draught fan which conveys air through the duct 36 to the airheater 18 and thence through the duct 37 to the coinbustion Chamber 1.

26 is a pipe or a plurality of pipes conveying the heated water, or a mixture of water and steam from the economizer 17 into the drum 3.

Figure 4 shows a double ended generator which is symrnetrical about the central axis. The generator shown incorporates one drum 3 and four evaporators 14, 14a, 14b, and 140, two evaporators being arranged on each side of the drum 3. The

saturated steam spaces of the drum 3 and the evaporators 14, 14a, 14h, and 14c are interconnected by means of the pipes 10, 10a, two junctions 11 and 11a being provided. From junction 11 one part of the saturated steam is led succes- 'i sively through the superheater element S, the heating element 14 arranged in the evaporator 9, the superheater element 8b, the heating element 14h, arranged in the evaporator 9b and through the final superheater 7. From junction 11a the other part of the saturated steam is led in a parallel path successively through the superheater element 8a, the heating element 14a, arranged in evaporator 9a, the superheater element 80, the

heating element 14c arranged in the evaporator 90 and through the final superheater 7a.

The combustion products leave the combustion Chamber 1 through two outlets, one being arranged between the Sections 6 of the upper water tubes 5-6 and the other between the Sections 6a of the opposite water tubes 5a-6a.

The arrangement shown in Fig. 5 is somewhat similar to the one shown on Fig. 3. The water tubes 40 which form the continuation of the water 1.

tubes 2 lining the rear of the Combustion chamber 1 are, however, arranged behind the superheater Chamber 4 in the direction of flow of the combustion products. Suitable spaces are left between the tubes 40 to provide a passage for the combustion products from the superheater chamber 4 to the economizer 17.

It will be seen that in this arrangement the combustion products do not pass across a row of water tubes before entering the superheater Chamber 4, The tubes 2 lining the rear of the combustion Chamber 1 are, however, bent in their upper part so as to form a horizontal V-shaped projection 38-39. The tubes 2 are provided with fins or covered with ref'ractory or other blocks along their whole length including the projection 38-39, so that this projection eifectively protects the superheater elements '7 and 8 from direct exposure to the furnace fiame. Part 39 of the projcction forms the bottom of the superheater chamber 4.

The tubes 2b which line the front of the combustion chamber 1 are connected at the top of the tubes al which discharge into the drum 3. The tubes 41 form the top of the superheater chamber 4.

An alternative position of the drum 3 is shown in dotted lines at 3a.

It will be evident that many modifications may be made in the construction, arrangement and operation of the generator without departing from the scope of the nvention.

I claim:--

1. In combination, a water tube boiler, a plurality of separate evaporators, a first superheater element receiving steam from said boiler and evaporators, heating elements in the water spaces of the evaporators, the heating element in the first evaporator receiving steam from said first superheater element, and a plurality of additional superheater elements alternating with the heating elements of the succeeding evaporators, said additional superheater elements receiving steam from the boiler and the evaporators after such steam is de-superheated in the said heating elements.

2. A steam generating plant comprising a furnace, a plurality of steam and water tubes surrounding said furnace, a boiler drum into which said steam and water tubes discharge, a plurality of evaporato-r drums, a heating element for each evaporator drum and a plurality of superheater elements through which all the steam generated in the boiler drum and the evaporators is passed in alternation with the heating elements in the evaporators.

3. In a steam generating plant the combination of a furnace, steam and water tubes forming walls of said furnace, a steam and water drum into which said steam and water tubes discharge, the steam and water tubes lining the upper rear portionof the furnace Chamber being bent to form a superheater chamber through which the furnace gases pass, an evaporator connected to the steam and water drum on the steam side, a Valve in the steam connection between the evaporator and the steam and water drum, a heating element disposed in said evaporator and a plurality of superheater elements disposed in said superheater char'nber, one of said superheater elements being connected to superheat steam passing therethrough from the steam and water drum and the evaporator in countercurrent to the direction of flow of the flue gases and to discharge such steam Vinto the heatng element in the evaporator, and a final superheater element through which the steam passes from the heating element of the evapo-rator in the same general direction as the flow of the flue gases and in which such steam is re-superheated.

4. In a steam generator the combination of a furnace, a steam and water drum, a plurality of steam and water tubes surrounding said furnace in a substantially bottle-shaped configuration, and of which the upper portions form superheater chambers, said steam and water tubes discharging at their upper en'ds into said steam and water drum, a plurality of evaporator vessels connected on their steam sides to the steam side of the steam and water drum, a plurality of heating elements disposed, respectively, in said evaporator vessels, and a plurality of superheater elements alternating in series with the heating elements of the evaporators and disposed in said superheater chambers.

5. In a steam generator, a steam and water drum, a plurality of steam and water tubes surrounding a furnace structure and connected with said steam and water drum, the upper part of the rear bank of said tubes being disposed in a horizontal V-shaped configuration projecting over the furnace chamber and forming a bafile and also forming the underside of a superheater Chamber through which'the products of combustion of the furnace pass, an evaporator vessel of which the steam and water spaces communicate, respectively, with the steam and water spaces of said steam and water drum, a heating element in said evaporator, a superheater element disposed in said superheater Chamber through which steam from the steam and water drum and the evaporator vessel passes in counter direction to the fiow of the fiue galses and from which superheated steam is delivered to the heating element in the evaporator Vessel, and a second superheater element through which steam passes from the heating element in the eVapo-rating vessel in the same direction as the flow of the flue gases and in which such steam is re-superheated.

6. A steam generating plant comprising a furnace, a plurality of steam and water tubes surrounding said furnace, a boiler drum into which said steam and water tubes discharge, a plurality of evaporator drums, a heating element for each evaporator drum, a pipe connecting the inlet and outlet ends of each of said heating elements, a valve in each of said pipes, and a plurality of superheater elements through which all the steam generated in the boiler drum and the evaporators is passed in alternation with the heating elements in the evaporators.

KARL BAUMANN. 

